Help my car just started rattling from under the car for some reason near the catalytic converter does anyone know what it can be pls help I also have check engine light for random misfire according to the scanner I need valve covers I have noticed oil on top of the valve cover only almost as if oil is coming out from the oil cap section even tho it’s tight the top of my valve cover is covered in oil I checked my spark plugs and no oil on them the valve cover also isn’t leaking from the gaskets